1. Field of the Invention
This invention relates generally to arrays of radiating and receiving elements, and more particularly to phased arrays of radiating and receiving elements.
2. Description of Related Art
Phased arrays of radiating and receiving elements such as, but not limited to antenna elements, are generally constructed with periodic rectangular or triangular grids. However, periodic grids have the disadvantage that when the element spacing much exceeds one-half wavelength (xcex/2) of the operating frequency, large grating lobes appear, especially when the antenna is electronically scanned. Accordingly, there is a constant effort in the field of antenna design to design phased array antennas which substantially reduce or eliminate grating lobes.
Accordingly, it is an object of the present invention to provide an improvement in antenna arrays.
It is another object of the present invention to provide an improvement in phased array antennas.
It is a further object of the present invention to provide an improvement in phased array antennas which ameliorates grating lobes.
It is still another object of the present invention to provide an improvement in phased array antennas which provides a sparse grid which reduces element density per unit area and thus reduces cost.
These and other objects are achieved by a sparse array antenna comprised of a packed logarithmic spiral lattice of radiating elements.
In one aspect of the invention, a phased array antenna is provided comprising a packed logarithmic spiral lattice arrangement of uniformly placed radiating elements, generally arranged according to the polar equations r and xcex8 such that       r    =                  d                  π                    ⁢              n              ,            and      ⁢              xe2x80x83            ⁢      θ        =          2      ⁢              xe2x80x83            ⁢      π      ⁢              xe2x80x83            ⁢      τ      ⁢              xe2x80x83            ⁢      n        ,      n    =    1    ,  …  ⁢      xe2x80x83    ,  N
where n is the number of elements, d is the equivalent one-dimensional linear spacing in wavelengths between one antenna element to another, and xcfx84 is the golden ratio   τ  =                    1        +                  5                    2        ≈          1.618      .      
Further scope of applicability of the present invention will become apparent from the detailed description provided hereinafter. However, it should be understood that the detailed description and specific example, while disclosing the preferred embodiment of the invention, is given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.